Wind turbines comprise a tower and a nacelle placed on top of that tower, whereby the nacelle is equipped with a rotor which rotates due to the impact of wind. In the nacelle, the rotational movement of the rotor is used to generate electric power.
Large wind turbine towers often comprise a number of tower segments, e.g. made of steel, which when assembled together form the complete wind turbine tower. The assembly of large wind turbine towers—in particular under offshore conditions, but also onshore—consumes a lot of time, effort, and financial resources. The standard state of the art is to assemble a wind turbine tower by attaching a number of brackets to an end flange of a tower segment and to connect a number of wires to these brackets. These wires are connected to a crane or to a similar raising machine and the tower segment is raised and transported to the site of assembly where it is connected either to a foundation of the wind turbine tower or to a lower tower segment to which the tower segment in question is then attached by e.g. bolting. After such assembly steps, the wires have to be disconnected from the tower segment, as well as the brackets, and the same procedure must be re-done for each tower segment until the complete wind turbine tower is established.
Such a procedure is very time-consuming and complicated in that it implies an attachment of both brackets and wires to the tower flange first and a detachment of both after the assembly process of each tower segment. In particular, it implies that staff has to manually attach the brackets and wires and later detach them again. This also constitutes a certain potential danger for staff, in particular in the upper operating heights of the wind turbine tower which can have up to 150 meters of height or even higher. The enormous need of installation time also means a large consumption of resources as for instance under offshore conditions, an installation vessel is necessary to carry the crane. The use of such vessel is very costly and thus any reduction of usage time of such vessel implies an enormous saving. Similar effects can be seen on onshore sites, with a lower, but still substantial cost factor. Furthermore, the forces and tensions inflicted on the tower flange during raising and transport is enormous: potentially (depending on wind conditions), at each bracket connection to the wires the full load of the complete tower section can occur so that the flanges must be designed very stable and large.
EP 2 402 278 B1 describes an arrangement for raising a tower segment of a wind turbine. It comprises a beam and a cross beam along both of which holding members are attached which holding members can engage with a flange of a tower segment when moved along the beam and cross-beam. The holding members are moved manually or by a motor into a desired operating position at which they can engage with a counter-shape of the tower segment.